Preparation of 4-amino-1,2,4-triazol-5-ones

Abstract

A process for the preparation of 4-amino-1,2,4-triazol-5-one of the formula ##STR1## in which R represents unsubstituted or substituted alkyl, alkenyl, cycloalkenyl, cycloalkyl, aralkyl, aryl or heterocyclyl, which comprises reacting a carbodihydrazide of the formula ##STR2## with a nitrile of the formula R--C.tbd.N (III) The carbodihydrazide of the formula (II) may be produced in a preliminary stage by reacting a carbonic acid derivative with hydrazine or hydrazine hydrate.

We claim: 
     
       1. A process for the preparation of a 4-amino-1,2,4-triazol-5-one of the formula ##STR19## in which R represents in each case straight-chain or branched alkyl or alkenyl having up to 8 carbon atoms, the alkyl or alkenyl in each case being unsubstituted or substituted by C 3  -14 C 6  -cycloalkyl, phenyl, C 1  -C 4  -alkoxy, C 1  -C 4  -alkylamino, di-(C 1  -C 4  -alkyl)-amino, hydroxy, amino or halogen, or R represents cycloalkenyl or cycloalkyl having in each case up to 6 carbon atoms, the cycloalkenyl or cycloalkyl in each case being unsubstituted or substituted by hydroxyl, amino, halogen, phenyl, C 1  -C 4  -alkoxy, C 1  -C 4  -alkylamino or di-(C 1  C 4  -alkyl)-amino, or R represents benzyl, phenyl, pyridyl or thienyl, which comprises (A) reacting a carbonic acid derivative of the formula ##STR20##  in which X and Y in each case represent halogen, amino, straight-chain or branched C 1-6  -alkoxy, phenoxy; or   X and Y together represent straight-chain or branched C 2-6  -alkylenedioxy, with hydrazine or hydrazine hydrate to form a carbodihydrazide of the formula ##STR21##  (B) reacting the carbodihydrazide of the formula (II) with a nitrile of the formula   R--C≡N                                               (III)        in situ.   
     
     
       2. The process according to claim 1 in which R represents methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, tert-pentyl, cyclopentenyl, cyclohexenyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl, which are in each case unsubstituted or mono-, di- or trisubstituted by substituents independently selected from the group consisting of fluorine and chlorine, or R represents benzyl or phenyl.   
     
     
       3. The process according to claim 1, wherein the reaction is carried out at a temperature between about 20° C. to about 250° C. 
     
     
       4. The process according to claim 1, wherein between about 0.5 to about 3 mol of nitrile of formula (III) are employed per mol of carbodihydrazide of the formula (II). 
     
     
       5. The process according to claim 1, wherein the reaction is carried out in the presence of a reaction auxiliary, which is a metal compound selected from the group consisting of dibutyltin dichloride, dimethyltin dichloride, dibutyltin oxide, hexabutyldistannoxane, butylstannonic acid, dibutyltin dilaurate and dimethyltin oxide. 
     
     
       6. The process according to claim 1, wherein the reaction is carried out in the presence of an aprotic diluent and a reaction auxiliary, which is a H-acid compound selected from the group consisting of phenol, ethylene glycol, propylene glycol, diethylamine, dipropylamine and dibutylamine.